In radio-frequency circuits, a multiplicity of different frequencies arise during operation. These radio-frequency signals and their superimpositions are emitted by the circuit if the metal structures of the circuit form an antenna for the interference radiation. By way of example, in cellular telephones a defined radiation power emerging from the cellular telephone is obligatory.
Moreover, circuits have to be protected against influences from incoming signals and radiation. For shielding radio-frequency signals, by way of example, the complete system comprising the circuit can be shielded by a fully shielded metallic housing. In order to save costs and to be able to reduce the size of the circuits and systems, instead of shielding the entire system, it is also possible to shield the circuits or electronic devices individually.
Conventionally, for this purpose, by way of example, a housing composed of metal is applied on the top side of the carrier of the device. In this case, tolerances in the arrangement of the metal housing on the carrier, the thickness of the metal and the required contact area have to be taken into account, which increases the size of the device.
In this case, it is necessary not only to protect the circuit as a whole against an emission and/or against influences from incoming signals and radiation, but also to electromagnetically shield individual regions of the circuit among one another.
The heat occurring during operation from electronic components of the circuit should also be dissipated from the components during operation.
For the purpose of electromagnetic shielding, by way of example, conventionally a panel comprising a substrate, an encapsulation arranged thereon and electronic components enclosed thereby is scribed to an extent such that conductive layers of the substrate are uncovered, but the substrate is not completely severed. A metal layer is thereupon applied to the partly cut panel, said metal layer serving for radio-frequency shielding. Only afterward is the panel completely severed and thus singulated to form the individual electronic devices. In this case, for the panel the cutting tolerances have to be taken into account and, moreover, a projection is left behind at the edge of the devices. This also leads to an increased space requirement. One such method is disclosed for example in U.S. Pat. No. 7,451,539 B2.
It is desirable to specify an electronic device and a method for producing a plurality of electronic devices which makes possible compact electronic devices. Moreover, the intention is for a shielding of regions of the respective devices and a heat dissipation to be reliably possible.
In one embodiment of the invention, a method for producing a plurality of electronic devices comprises providing a panel comprising an areally extended substrate, an encapsulation and electronic components, such as, for example, filters, transistors, resistors, capacitors and/or inductances. The panel is singulated to form a plurality of electronic devices. After singulation, a respective electromagnetic protective layer is applied to each of the electronic devices, such that the electromagnetic protective layer covers the side faces of the substrate that are exposed by the singulation.
As a result of applying the electromagnetic protective layer after singulating the panel to form the plurality of electronic devices, it is possible to reduce the size of the electronic devices. No contact area for an external shielding housing need be provided on the substrate. Moreover, no projection remains at the edge of the substrate, as in the case of a two-stage singulation process, if the panel is singulated with one cut.
By way of example, the electromagnetic protective layer is applied by means of a sputtering deposition method.
In one exemplary embodiment, at least one partial layer of the electromagnetic protective layer is applied to the electronic device by means of sputtering deposition. In a further embodiment, the electromagnetic protective layer is applied in electroless fashion. At least one partial layer of the electromagnetic protective layer is applied in electroless fashion, for example. In one embodiment, a partial layer comprising titanium and/or a partial layer comprising copper are/is applied by means of sputtering deposition and a partial layer comprising nickel is thereupon applied to the first partial layers in electroless fashion.
In one embodiment, the electromagnetic protective layer is applied such that the side faces of the electronic devices which are oriented transversely with respect to the main propagation direction of the electronic devices or of the substrate are in each case completely covered by the electromagnetic protective layer. This is possible since the panel and thus also the substrate are firstly singulated and only afterward is the electromagnetic protective layer applied. Therefore, during the application of the protective layer, the electronic devices of the plurality of electronic devices are not connected, even over a partial region of the substrate, such that in particular the side faces of the substrate are exposed during the application of the electromagnetic protective layer.
In one embodiment, an notch, in particular an undercut, is formed, for example cut beginning at the underside, into the substrate in a region adjoining the underside of the substrate. As a result, in the embodiment the electromagnetic protective layer is applied such that the side faces of the electromagnetic devices which are oriented transversely with respect to the main propagation direction of the electronic devices or of the substrate are in each case completely covered by the electromagnetic protective layer, apart from in the region of the notch or of the undercut, in which no partial layer is deposited during the sputtering deposition. Therefore, the nickel layer, too, is not applied in the notch.
In accordance with further aspects of the invention, the method for producing a plurality of electronic devices comprises providing an areally extended panel, in turn comprising: a substrate and a plurality of electronic components arranged on the substrate. Furthermore, the panel comprises an encapsulation covering the plurality of components on the substrate.
The panel is singulated to form the plurality of electronic devices. After singulation, a respective electromagnetic protective layer is applied to the devices of the plurality of electronic devices, such that the electromagnetic protective layer covers the side faces of the substrate that are exposed by the singulation, and such that the electromagnetic protective layer is in each case thermally and/or electrically coupled to a region of the electronic device that is enclosed by the encapsulation.
As a result of applying the electromagnetic protective layer after singulating the panel to form the plurality of electronic devices, it is possible to reduce the size of the electronic devices and at the same time to realize a reliable electromagnetic shielding and heat dissipation. No contact area for an external shielding housing need be provided on the substrate. Moreover, no projection remains at the edge of the substrate, as in the case of a two-stage singulation process, if the panel is singulated with one step.
In embodiments, the electromagnetic protective layer is applied by means of a sputtering deposition method. In embodiments, the electromagnetic protective layer is applied such that the side faces of the electronic devices which are established transversely with respect to the main propagation direction of the electronic devices or of the substrate are in each case completely covered by the electromagnetic protective layer. This is possible since the panel and thus also the substrate are firstly singulated and only afterward is the electromagnetic protective layer applied. Therefore, during the application of the protective layer, the electronic devices of the plurality of electronic devices are not connected, even over a partial region of the substrate, such that in particular the side faces of the substrate are exposed during the application of the electromagnetic protective layer.
In embodiments, for the purpose of thermal and/or electrical coupling, cutouts are introduced into the encapsulation, electrically and/or thermally conductive material being arranged in said cutouts. In further embodiments, coupling elements are arranged prior to applying the electromagnetic protective layer, which coupling elements are subsequently thermally and/or electrically coupled to the electromagnetic protective layer after the latter has been applied.
In one embodiment of the invention, an electronic device comprises an areally extended substrate, and an encapsulation arranged on a main face of the substrate. An electromagnetic protective layer completely covers a surface of the encapsulation that faces away from the substrate, and the side faces of the substrate that are directed transversely with respect to the surface.
Such an electronic device is compact and well shielded against radio-frequency radiation.
In particular, the electromagnetic protective layer covers the side faces of the encapsulation and of the substrate completely beginning at the surface of the encapsulation as far as an opposite underside of the substrate.
In accordance with further aspects of the invention, an electronic device comprises a substrate and at least one electronic component arranged on the substrate. An encapsulation covers the component on the substrate. The electronic device furthermore comprises an electromagnetic protective layer, which covers a surface of the encapsulation that faces away from the substrate, and the side faces of the substrate that are directed transversely with respect to the surface. The device furthermore comprises a thermal and/or electrical coupling, which couples the electromagnetic protective layer thermally and/or electrically to a region of the electronic device that is enclosed by the encapsulation.
In particular, the electromagnetic protective layer completely covers the side faces of the encapsulation and of the substrate.
An electromagnetic shielding of individual regions of the electronic device is made possible by the thermal and/or electrical coupling. In particular, the electronic component, comprising, for example, filters, transistors, resistors, capacitors and/or inductances, is electrically shielded by the electrical coupling that couples the electromagnetic protective layer to the region that is enclosed by the encapsulation. In this case, the electrical coupling is short-circuited to ground via the electromagnetic protective layer.
As a result of the thermal and/or electrical coupling that thermally couples the electromagnetic protective layer to the region that is enclosed by the encapsulation, the coupling is designed to dissipate heat that occurs from the electronic component during operation, for example, via the electromagnetic protective layer. Reliable operation of the electronic device is possible as a result.
In embodiments, the thermal and/or electrical coupling is embodied as part of the electromagnetic protective layer which extends into the region that is enclosed by the encapsulation. In further embodiments, the coupling comprises a separate coupling element, which is thermally and/or electrically coupled to the electromagnetic protective layer and to the region that is enclosed by the encapsulation.
In embodiments, the thermal coupling is embodied as part of the electromagnetic protective layer, and in the embodiments, the electromagnetic protective layer is in direct contact with the electronic component. In further embodiments, the electronic component is thermally coupled to the electromagnetic protective layer via the coupling element, wherein the coupling element is in direct contact with the electrical component.
In accordance with further aspects of the invention, an electronic device comprises a substrate and at least one electronic component arranged on the substrate. An encapsulation covers the component on the substrate. The electronic device furthermore comprises an electromagnetic protective layer, which completely covers a surface of the encapsulation that faces away from the substrate, and the side faces that are directed transversely with respect to the surface, from the surface of the encapsulation as far as an opposite underside of the substrate. The device furthermore comprises a thermal and/or electrical coupling, which couples the electromagnetic protective layer thermally and/or electrically to a region of the electronic device that is enclosed by the encapsulation.
Elements that are identical, of identical type and act identically may be provided with the same reference signs in the figures. The elements illustrated and their size relationships with respect to one another should not be regarded as true to scale, in principle; rather, individual elements, such as, for example, layers and regions, may be illustrated with exaggerated thickness or size dimensions in order to enable better illustration and/or in order to afford a better understanding.